Method and apparatus for polymer application to intracorporeal device

ABSTRACT

A method and apparatus for applying a polymer coating on an elongated substrate, preferably an elongate intracorporeal device in the form of a guidewire. An extrudable polymer cartridge is moved by a cartridge advancement mechanism into a guide chamber which is heated at an end with a die or orifice through which a desired portion of a guidewire may pass and be coated. Parameters such as guide chamber temperature, pull speed and force exerted by the cartridge advancement mechanism may be controlled with a computer program in order to achieve repeatable results. The guide chamber, extrudable polymer cartridge, die, and push tube may all be made from polymer components which can be reused or disposed of after a single use. The extrudable polymer cartridge may have a variety of configurations including multiple layers of different materials, eccentric shapes, multiple lumens for multiple elements to be drawn through and coated and asymmetric disposition of different materials with respect to the longitudinal axis as viewed in a transverse cross section which can give bending properties having a preferred direction in the coated guidewire or device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application of a application having U.S. Ser. No.10/161,786, filed Jun. 4, 2002 now U.S. Pat No. 6,599,557, which is adivisional of U.S. Ser. No. 09/441,695 filed Nov. 16, 1999, now U.S.Pat. No. 6,419,745 B1 issued Jul. 16, 2002, the contents of all of whichare hereby incorporated by reference.

BACKGROUND

This invention relates to an apparatus and method for applying a polymercoating to a desired length of an elongate member, preferably to anelongate intracorporeal device. More specifically, the invention relatesto a method and apparatus for applying a polymer coating to a desiredlength of an intracorporeal guiding device or guidewire. The inventioncan also be used to apply a polymer coating to a length of any othersuitable device such as a vascular stent, cardiac pacing leads, cathetertubings, braided or solid electrical wire, coaxial cable or the like.

In a typical prior art process for applying a polymer coating over anelongate member, an extrusion machine is used which has a heated diehead with channels leading to a heated chamber within the die head.Melted polymer is forced into the chamber with a lead screw which forcessolid polymer, usually in the form of pellets, into the heated chamber.The elongate member to be coated is passed through the back end of thedie head into the chamber and out of an orifice in an extrusion diewhich is attached to the extrusion head. The elongate member is thenpulled through the die as melted polymer is forced into the die head andonto the elongate member. Normally, the orifice in the die will belarger than the elongate member so that a desired amount of the meltedpolymer remains on the elongate member after passing through theorifice. After passing through the orifice, the melted polymer on theelongate device cools and the coating process is complete.

A prior art process such as that described above is well suited in manycases for coating long lengths of durable elongated members orsubstrate. The equipment used is large, expensive and cumbersome and candamage a fragile substrate being pulled through the device, such as aguidewire distal section with a small diameter helical coil. Inaddition, the amount of effort and expense required for a given set upoften does not justify small runs of material. Also, the equipment isnot Nell suited for coating short lengths of discrete elongated members,such as guidewires or the like, because adjusting the settings toachieve desired coating dimensions and parameters is usually a processthat requires several minutes of running time in order for equilibriumof the dynamic to be established and stabilization of the process tooccur. This often requires running many feet of substrate through thedie head prior to stabilization which is not possible with a guidewirewhich is only several feet long.

Another difficulty exists in trying to vary the coating parametersdynamically in a controlled fashion in order to achieve a coating whichhas varying parameters such as a transverse dimension along an axialdirection. As mentioned above, the usual coating equipment of the priorart is large and cumbersome and it is impractical to vary parameterssuch as temperature of the die, speed of pull, and pressure exerted onthe melted polymer over short lengths of an elongate member substrate.

What has been needed is an apparatus suitable for applying a variety ofpolymer coatings to a discrete length of a fragile intracorporeal devicesubstrate with quick response time for variation in extrusionparameters. What has also been needed is an apparatus suitable forcoating an elongate intracorporeal member that has automatable controlof extrusion parameters such as die temperature, pull speed and pressureapplied to melted polymer which can produce repeatable control ofdiameter and other dimensions of the polymer coating applied. Inaddition, it is desirable to have an apparatus suitable for reliablyapplying a polymer coating with a constant outer transverse dimension toa substrate which varies in transverse dimension or diameter along itsaxial length.

SUMMARY

The invention is directed to an apparatus for applying a polymer coatingto an elongate intracorporeal device, specifically, a guidewire. In oneembodiment, the apparatus can have a guide chamber with an input endhaving an input port and an output end. An extrusion orifice is disposedat the output end of the guide chamber and is in fluid communicationwith the guide chamber. The extrusion orifice can be configured to allowan elongate intracorporeal device or other substrate to pass through orbe pulled through the extrusion orifice with a desired thickness orconfiguration of polymer coating on the elongate intracorporeal deviceor substrate. The orifice can be configured to leave a fixed thicknessof polymer over the elongate intracorporeal device, or the orifice canbe shaped so as to leave a desired profile or configuration of polymercoating on the device, e.g., an orifice having an oval, square ortriangular cross section.

A heater member is disposed in thermal communication with the guidechamber and serves to heat a desired portion of the guide chamber. Acartridge advancement mechanism is disposed adjacent the guide chamber.In use, an extrudable polymer cartridge is placed within the guidechamber of the apparatus. The cartridge advancement mechanism can beconfigured to axially translate the extrudable polymer cartridge intothe guide chamber in a direction of extrusion, i.e., a direction fromthe input end of the guide chamber to the output end of the guidechamber. The extrudable polymer cartridge can have a lumen extendinglongitudinally through the cartridge with the lumen being sized orconfigured to accept the elongate intracorporeal device. The lumen ofthe extrudable polymer cartridge is typically sized to allow theelongate intracorporeal member to slide freely within the lumen.

In another embodiment, a guide chamber is formed by a guide tube withthe guide chamber being disposed within the guide tube. The guide tubehas an input end with an input port in fluid communication with theguide chamber and an output end. A die having an extrusion orifice isdisposed at the output end of the guide tube such that the extrusionorifice is in fluid communication with the guide chamber. The extrusionorifice of the die can be configured to allow an elongate intracorporealdevice to pass through the die with a desired configuration of polymercoating on the member. A heater member is disposed in thermalcommunication with the guide tube for heating a desired portion of theguide tube or die.

A push tube is disposed at least partially and slidably within the guidechamber. The push tube has a contact end, an attachment end, alongitudinal axis and at least one inner lumen extending substantiallyparallel to the longitudinal axis of the push tube. The inner lumen ofthe push tube is configured to accept a desired elongate intracorporealdevice. In use, an extrudable polymer cartridge, having similarproperties to the extrudable polymer cartridge discussed above, can bedisposed within the guide chamber between the extrusion orifice of thedie and the contact end of the push tube.

In another embodiment, a puller is disposed adjacent the output end ofthe guide tube. The puller can be configured to be temporarily securedto a desired portion of the elongate intracorporeal device and apply aforce and movement in the direction of extrusion on the device. A pushtube actuator is disposed adjacent the input end of the guide tube andis configured to apply a force and movement on the extrudable polymercartridge disposed within the guide chamber. Specifically, the push tubeis disposed between the extrudable polymer cartridge and the push tubeactuator and mechanically couples the push tube actuator to theextrudable polymer cartridge. A computing machine may be electronicallyconnected to a temperature sensor coupled to the heater member, thepuller and the push tube actuator. The computing machine can be used torepeatably control the temperature of the heating member, the rate ofaxial movement of the elongate intracorporeal device in a direction ofextrusion by controlling the rate of axial movement of the puller, andthe rate of feed or axial movement in the direction of extrusion of theextrudable polymer cartridge by controlling the rate of movement orforce applied to the push tube in the direction of extrusion.

One of the advantages of the apparatus for applying a polymer coating isthat many of the components of the apparatus can be manufactured fromdisposable polymer materials that are made to be modular and avoid theneed for cleaning of components. For example, both the guide tube andthe die can be made from a variety of high temperature polymers such aspolyimide (PI), polytetraflouroethylene (PTFE), liquid crystal polymer(LCP) and polyetheretherkeytone (PEEK) This allows a subassemblyconsisting of the guide tube, die and extrudable polymer cartridge to beloaded into a corresponding guide tube assembly for each elongateintracorporeal device to be coated. When the device has been coated, thesubassembly can be disposed of and a new subassembly loaded into theguide tube assembly. This eliminates the need for time consumingcleaning operations and allows the use of varying die configurations andextrudable polymer cartridge materials from one elongate intracorporealdevice to the next.

Another advantage of the apparatus for applying a polymer coating is theability to reliably maintain concentricity of the coating applied to theelongate intracorporeal device. Where such concentricity is desired, theuse of an extrudable polymer cartridge having an inner lumen which isconcentric to a longitudinal axis of the cartridge provides centering ofthe elongate intracorporeal device prior to passing through theextrusion orifice. As the extrudable polymer cartridge is melted at theoutput end of the guide chamber and applied to the elongateintracorporeal device, the unmelted portion of the cartridge immediatelyadjacent a melt zone of the extrudable polymer cartridge continuouslyprovides centering of the elongate intracorporeal device within theguide chamber and extrusion orifice. Also, the melted portion of theextrudable polymer cartridge at the melt zone can be applied evenly in aradially inward direction from all sides of the elongate intracorporealdevice in embodiments of the invention where the inner lumen of theextrudable polymer cartridge is concentric with the longitudinal axis ofthe cartridge. This can also facilitate maintaining concentricity of thepolymer coating.

In use, an extrudable polymer cartridge is placed in the guide chamberof the guide tube between the extrusion orifice and the contact end ofthe push tube. An elongate intracorporeal device is loaded into the die,at least of a portion of the inner lumen of the extrudable polymercartridge and optionally the inner lumen of the push tube. The elongateintracorporeal device is then temporarily secured to the puller and theheater member activated. When the portion of the extrudable polymercartridge adjacent the die attains a desired temperature and viscosity,the puller and cartridge advancement mechanism, typically consisting ofa push tube actuator, are activated. This advances both the elongateintracorporeal device and extrudable polymer cartridge in the directionof extrusion, i.e. in a direction from the input end of the guidechamber to the output end of the guide chamber.

The coating process can be terminated in several ways. The process maybe terminated when an end or extremity of the elongate intracorporealdevice is drawn through the output end of the guide chamber and die.This method will typically coat the entire end or extremity of theelongate intracorporeal device. Alternatively, the advancement of theextrudable polymer cartridge can be stopped by deactivating thecartridge advancement mechanism while continuing to advance the elongateintracorporeal device in the direction of extrusion. In this way, themelted extrudable polymer cartridge is no longer feeding into theextrusion orifice and coating the elongate intracorporeal device. Also,the amount of material in the extrudable polymer cartridge may belimited to suffice for coating only a desired portion of an elongateintracorporeal device. As the extrudable polymer cartridge is advancedin the direction of extrusion and polymer coating is applied, thecartridge gets shorter. The process continues until the contact end ofthe push tube hits the die and melted polymer material is no longer fedinto the extrusion orifice and the coating process stops, although theelongate intracorporeal may continue to be pulled or advanced in thedirection of extrusion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view in partial section of an apparatus forapplying a polymer coating to an elongate intracorporeal device havingfeatures of the invention.

FIG. 2 is an elevational view in partial section of the guide tubeassembly shown in FIG. 1 taken along lines 2—2 in FIG. 1.

FIG. 3 is a transverse cross sectional view of the guide tube assemblyshown in FIG. 2 taken along lines 3—3 in FIG. 2.

FIG. 4 is a transverse cross sectional view of the guide tube assemblyshown in FIG. 2 taken along lines 4—4 in FIG. 2.

FIG. 5 is an elevational view in longitudinal cross section of the diein the guide tube assembly shown in FIGS. 1-4, having features of theinvention

FIGS. 6A-6C are transverse cross sectional views of the die shown inFIG. 5 taken along lines 6—6 in FIG. 5, having various extrusion orificeconfigurations.

FIG. 7 is an elevational view in partial section of a tandem apparatusfor applying a polymer coating to an elongate intracorporeal devicehaving features of the invention.

FIG. 8 illustrates an elevational view in section of a guide tubeassembly having features of the invention.

FIG. 9 is a transverse cross sectional view of the guide tube assemblyof FIG. 8 taken along lines 9—9 in FIG. 8.

FIG. 10 illustrates an extrudable polymer cartridge having features ofthe invention.

FIG. 11 is a transverse cross sectional view of the extrudable polymercartridge of FIG. 10 taken along lines 11—11 in FIG. 10.

FIG. 12 illustrates an extrudable polymer cartridge having features ofthe invention.

FIG. 13 is a transverse cross sectional view of the extrudable polymercartridge of FIG. 12 taken along lines 13—13 in FIG. 12.

FIG. 14 illustrates an extrudable polymer cartridge having features ofthe invention.

FIG. 15 is a transverse cross sectional view of the extrudable polymercartridge of FIG. 14 taken along lines 15—15 in FIG. 14.

FIG. 16 illustrates an extrudable polymer cartridge having features ofthe invention.

FIG. 17 is a transverse cross sectional view of the extrudable polymercartridge of FIG. 16 taken along lines 17—17 in FIG. 16.

FIG. 18 illustrates an extrudable polymer cartridge having features ofthe invention.

FIG. 19 is a transverse cross sectional view of the extrudable polymercartridge of FIG. 18 taken along lines 19—19 in FIG. 18.

DETAILED DESCRIPTION

FIGS. 1-4 illustrate a polymer coating apparatus 10 for applying apolymer coating 11 to an elongate intracorporeal device 12. A guide tubeassembly 13 is removably secured to a guide tube assembly mount 14. Theguide tube assembly mount 14 is secured to a mounting surface 15, whichcan be an even vertical surface, but which can have any desiredconfiguration or orientation. A heater member 16 is secured in thermalcommunication with a guide tube housing 17 of the guide tube assembly 13and serves to supply heat energy to a desired portion of the guide tubeassembly 13. The guide tube assembly 13 includes a guide tube housing 17which has an input end 18 and an output end 19. The output end 19 has athreaded portion 22 and the input end 18 has a retainer lip 23. Aretainer cap 24 is threaded onto the threaded portion 22 of the outputend 19 of the guide tube housing 17.

The guide tube housing 17 can be made of a conductive material such asstainless steel, a machineable insulative material such as Vespel® orany other suitable material. A guide tube 25 having an input end 26 , anoutput end 27 and a guide chamber 28 disposed within the guide tube 25is disposed within the guide tube housing 17. The input end 26 of theguide tube 25 is disposed against the retainer lip 23 of the guide tubehousing 17. A die 31 having an input end 32 and an output end 33 isdisposed within the guide tube housing 17 with the input end 32 of thedie 31 against the output end 27 of the guide tube 25. An optionalcentering insert 34 having an input end 35 and an output end 36 isdisposed within the guide tube housing 17 with the input end 35 of thecentering insert 34 against the output end 33 of the die 31. Theretainer cap 24 with a center hole 37 is threaded onto the threadedportion 22 of the guide tube housing 17 to hold the guide tube 25, dieand centering insert 34 within the guide tube housing 17.

In one embodiment, the guide tube 25 has a length of about 0.5 to about5 inch, specifically about 1.0 to about 3.0 inch. The guide tube 25, die31 and centering insert 34 can have an outer diameter of about 0.03 toabout 0.2 inch, specifically about 0.05 to about 0.1 inch. The guidetube 25 of the embodiment can have a wall thickness of about 0.005 toabout 0.015 inch. In other embodiments, the length, outer diameter andwall thickness of the guide tube 25 can vary significantly from thedimensions given above to suit the desired application. The guide tube25, die 31 and centering insert 34 can be disposable and made from ahigh temperature polymer such as PI, PTFE, LCP or PEEK.

As best shown in FIG. 1, a puller 40 is disposed adjacent an output end41 of the guide tube assembly 13 and has a clamp 42 aligned with thelongitudinal axis 43 of an inner lumen 44 of the die 31 for temporarilysecuring the elongate intracorporeal device 12 to the puller 40. Theclamp 42 temporarily secures a desired portion of the elongateintracorporeal device 12 to the puller 40 such that the elongateintracorporeal device 12 is centered within the inner lumen 44 of thedie 31. The puller 40 is slidably disposed on a puller track 45 and hasmotor 46 which mechanically engages the puller track 45 and moves thepuller 40 parallel to a longitudinal axis 47 of the guide tube assembly13.

A cartridge advancement mechanism 51 consisting of a push tube actuator52 and a push tube 53 is disposed adjacent an input end 54 of the guidetube assembly 13. The push tube actuator 52 is mechanically coupled tothe push tube 53 with the push tube 53 having a contact end 55 and anactuator end 56. The push tube 53 is configured to have the contact end55 slidably disposed within the guide chamber 28 of the guide tube 25and apply force to an extrudable polymer cartridge 57 disposed withinthe guide chamber 28 in a direction of extrusion. The direction ofextrusion is defined to be from the input end 54 of the guide tubeassembly 13 to the output end 41 of the guide tube assembly 13 asindicated by arrows 58.

The push tube actuator 52 is slidably disposed on a push tube actuatortrack 61 such that a longitudinal axis 62 of an inner lumen 63 of thepush tube 53 is aligned with the longitudinal axis 43 of the die 31 andlongitudinal axis 64 of an inner lumen 65 of the extrudable polymercartridge 57. A push tube actuator motor 66 is disposed on the push tubeactuator 52 and mechanically coupled to the push tube actuator track 61so as to enable the motor 66 to axially translate the push tube actuator52 on the push tube actuator track 61 along a longitudinal axis 47 ofthe guide tube assembly 13.

The elongate intracorporeal device 12 is disposed within an inner lumen67 of the centering insert 34, the extrusion orifice 68 of the die 31,the inner lumen 65 of the extrudable polymer cartridge 57 and the innerlumen 63 of the push tube 53. The elongate intracorporeal device 12 isalso shown as being disposed along the longitudinal axis 47 of the guidetube assembly 13. Other configurations may be used where the elongateintracorporeal device 12 is offset from the longitudinal axis 47 of theguide tube assembly 13.

A computer 71 is in electrical communication with an electronic controlunit 72 which is in electrical communication with a temperature sensor73 disposed in thermal communication with the heater member 16, a pullerposition indicator 74 disposed on the puller 40, and a push tubeactuator position indicator 75 disposed on the push tube actuator 52.The temperature sensor 73 provides an electrical signal to the computer71 indicating the temperature of the heater member 16. The pullerposition indicator 74 provides an electrical signal to the computer 71indicating the position of the puller 40 relative to the output end 41of the guide tube assembly 13. The push tube actuator position indicator75 provides an electrical signal to the computer 71 indicating theposition of the push tube actuator 52 relative to the input end 54 ofthe guide tube assembly 13. In addition, the computer 71 is electricallycoupled to the control unit 72 such that a signal from the computer 71can control the amount of power to the heater member 16, the speed anddirection of translation of the puller 40 and the speed and direction oftranslation of the push tube actuator 52.

In this way, the computer 71 can be programmed to repeatably control thetemperature of the heater member 16, the rate of pull of the elongateintracorporeal device 12 through the guide tube assembly 13 and the rateof feed of the extrudable polymer cartridge 57 into the guide chamber 28in the direction of extrusion. This enables the computer 71 torepeatably control the entire coating process for consistent coatingresults. The computer 71 may be a standard personal computer, or anysuitable substitute such as a custom integrated circuit or the like. Inaddition, the function of the computer 71 could be carried out withstandard analog circuitry of suitable configuration that would provide adesired and repeatable heater member 16 temperature, rate of pull of thepuller 40 and rate of feed of the push tube actuator 52.

In use, the retainer cap 24 is removed from the guide tube housing 17.The guide tube 25 is loaded into the guide tube housing 17 from theoutput end 19 of the guide tube housing 17 until the input end 26 of theguide tube 25 contacts the retainer lip 23 of the guide tube housing 17and the contact end 55 of the push tube 53 enters the guide tube chamber28 at the input end of the guide tube 25. The extrudable polymercartridge 57 is then loaded into the guide chamber 28 at the output endof the guide tube 25 until it contacts the contact end 55 of the pushtube 53. Next, the die 31 is loaded into the guide tube housing 17 withthe input end 32 of the die 31 adjacent the output end 27 of the guidetube 25. The centering insert 34 is then loaded into the guide tubehousing 17 with the input end 35 of the centering insert 34 adjacent theoutput end 33 of the die 31. The retainer cap 24 is then replaced whichconfines the guide tube 25, extrudable polymer cartridge 57, die 31 andcentering insert 34 within the guide tube housing 17.

The elongate intracorporeal device 12 is then inserted through the innerlumen 67 of the centering insert 34, the extrusion orifice 68 and innerlumen 44 of the die, the inner lumen 65 of the extrudable polymercartridge 57, and at least a portion of the inner lumen 63 of the pushtube 53. The elongate intracorporeal device 12 is then temporarilysecured to the puller 40 by the clamp 42. The coating cycle is thenstarted by supplying power to the heater member 16 which heats a desiredportion of the die 31, guide tube 25 and extrudable polymer cartridge 57which are adjacent and in thermal communication with the heater member16.

Thermal energy from the heater member 16 may be coupled to the die 31alone, the die 31 and the output end 27 of the guide tube 25 or the die31 and any desired portion of the guide tube 25. Also, it may be usefulin some embodiments to generate a temperature gradient along thecentering insert 34, die 31 and guide tube 25. In one embodiment, it ispreferable to concentrate most of the thermal energy on the die 31 andoutput end 27 of the guide tube 25.

As thermal energy is transferred to the extrudable polymer cartridge 57,it can begin to soften or melt at a melt zone 57A. When the portion ofthe extrudable polymer cartridge 57 adjacent the die 31 approaches adesired temperature or viscosity or both, force in the direction ofextrusion is applied to the extrudable polymer cartridge 57. This pushesthe melted or softened polymer material in the melt zone 57A of theextrudable polymer cartridge 57 into the input end 32 and inner lumen 44of the die 31 and onto the elongate intracorporeal device 12. When theforce in the direction of extrusion is initiated on the extrudablepolymer cartridge 57, the elongate intracorporeal device 12 issimultaneously advanced in the direction of extrusion so that as theextrudable polymer cartridge 57 is heated, melted, and forced into thedie 31. The melted extrudable polymer cartridge 57 is applied to themoving elongate intracorporeal device 12 in a radially inward directionas indicated by arrows 57B. As shown in FIG. 2, the extrudable polymercartridge 57 is applied evenly at the melt zone 57A from all directionsas indicated by arrows 57B. The evenly distributed inward radial forcehelps maintain the concentricity of the polymer coating 11 if the lumenof the extrudable polymer cartridge is concentric with the longitudinalaxis 64 of the extrudable polymer cartridge 57 and longitudinal axis 43of the die 31. The coating process is carried out continuously until adesired portion of the elongate intracorporeal device 12 has beencoated. The process may be terminated by exhaustion of the extrudablepolymer cartridge 57, cessation of the force in the direction ofextrusion on the extrudable polymer cartridge, or passage of anextremity 76 of the elongate intracorporeal device 12 through the die31.

In the embodiment of the polymer coating apparatus 10 shown in FIGS.1-4, the force in the direction of extrusion on the extrudable polymercartridge 57 is applied by the contact end 55 of the push tube 53 whichis mechanically coupled to the push tube actuator 52. One alternative tousing push tube actuator motor 66 to apply force and motion to the pushtube actuator 52 is to apply a substantially constant force in thedirection of extrusion on the push tube actuator 52 with an optionalconstant force spring 77. The constant force spring 77 may be secured toany suitable portion of the push tube 53, push tube actuator 52, guidetube assembly mount 14, or mounting surface 15. A suitable triggermechanism can be used to initiate the force from the constant forcespring 77 in the direction of extrusion at the appropriate time in thecoating cycle.

When the coating cycle is finished, the elongate intracorporeal device12 is removed from the guide tube assembly 13 and the puller 40. Theretainer cap 24 of the guide tube housing 17 is removed as well as thespent die 31, centering insert 34, guide tube 25 and extrudable polymercartridge 57. The push tube 53 is then reset to its original positionand a new guide tube 25, extrudable polymer cartridge 57, die 31 andcentering insert 34 loaded into the guide tube housing 17. It may bepossible to reuse the die 31, guide tube 25 or centering insert 34.Also, the new guide tube 25, die 31 and extrudable polymer cartridge 57may be loaded into the guide tube housing 17 in one connected modularunit or subassembly in order to lessen the time between coating cycles.

The temperature range of the heater member 16, die 31 and desiredportion of the guide tube 25 used for the process of the polymer coatingapparatus 10 can vary significantly depending on the desired result,size and material composition of the elongate intracorporeal device 12and material composition of the extrudable polymer cartridge 57. Forcoating an elongate intracorporeal device 12 consisting of a guidewire,in order to yield a finished outer diameter of about 0.012 to about0.016 inch, a temperature range of about 340 to about 390 degreesFahrenheit, specifically about 350 to about 380 degrees Fahrenheit istypical if using polyurethane for the extrudable polymer cartridge 57material.

As the temperature of the heater member 16 is changing as the coatingprocess is started, it may be desirable to trigger axial movement of theelongate intracorporeal device 12 in the direction of extrusion justprior to reaching the desired target temperature. For example, if theultimate target temperature of the heater member 16 is about 365 degreesFahrenheit, then the puller 40 may be triggered by programming of thecomputer 71 to start the puller 40 moving in the direction of extrusionwhen the heater member 16 reaches a temperature of about 362 degreesFahrenheit.

The rate of speed of pull of the elongate intracorporeal device 12through the guide tube assembly 13 can vary considerably depending onmany factors including the size and durability of the elongateintracorporeal device 12, the temperature of the heater member 16 andthe material of the extrudable polymer cartridge 57. For the examplegiven above, with an elongate intracorporeal device 12 of stainlesssteel having a desired finish outer diameter of about 0.012 to about0.016 inch, using polyurethane for the extrudable polymer cartridge 57,a typical rate of pull can be from about 0.25 to about 1.0 cm/second fordurable portions of the member 12, and about 0.05 to about 0.15cm/second for more fragile portions of the member 12, such as portionsof the elongate intracorporeal device 12 covered by a helical coil whichis subject to mechanical deformation. In one embodiment, the forceapplied to the extrudable polymer cartridge 57 by the push tube 53 viathe push tube actuator 52 can be from about 0.5 to about 10 pounds,specifically about 1.0 to about 2.0 pounds.

In another embodiment, the cartridge advancement mechanism 51, describedabove as consisting of a push tube actuator 52 coupled to a push tube 53can be replaced with a substantially constant force spring coupled tothe push tube so as to apply a substantially constant force in thedirection of extrusion on the extrudable polymer cartridge 57 during thecoating process. The amount of force can be similar to the forces notedabove with regard to the push tube actuator 52 embodiment.

FIGS. 5-6C illustrate an enlarged view of the embodiment of the die 31shown in FIGS. 2 and 4. The die 31 can be made from a variety ofmaterials, including high temperature polymers such as PI, PTFE, LCP andPEEK. The die 31 can also be made from metal or any other suitablematerial The die 31 has an input end 32, an output end 33 and an innerlumen 44. An extrusion orifice 68 is disposed at an output extremity 78of the inner lumen 44. The length 79 of the inner lumen 44 of the die 31can vary significantly depending on the desired result and numerousother factors. In one embodiment, the length of the inner lumen 44 canrange from about 0.02 to about 0.5 inch, specifically about 0.05 toabout 0.08 inch. A transverse dimension of the inner lumen 44 andextrusion orifice 68 of the die 31 in said embodiment can be from about0.01 to about 0.25 inch, specifically about 0.011 to about 0.015 inch.

The die 31 has an outer transverse dimension similar to an outertransverse dimension of the guide tube 25. An input taper 81 at theinput end 32 of the die 31 has an input taper angle 82. An optionaloutput taper 83 at the output end 33 of the die 31 has an output taperangle 84. Output taper angle 84 and input taper angle 82 can be fromabout 15 degrees to about 180 degrees, i.e. a flat cut end with notaper, specifically, from about 35 to about 45 degrees, and morespecifically, from about 36 to about 40 degrees. Although the extrusionorifice 68 of the die 31 shown in FIG. 5 has a round cross section asshown in FIG. 6A, the cross section of the extrusion orifice 68 can haveany desired configuration or shape such as the square configurationshown in FIG. 6B or the elliptical configuration shown in FIG. 6C. Anyother suitable extrusion orifice 68 configuration or cross sectionalshape can be used to achieve a desired result.

FIG. 7 illustrates a tandem polymer coating apparatus 86 having a firstpolymer coating apparatus 87 in line with a second polymer coatingapparatus 88. The various components of the first and second polymercoating apparatus 87 and 88 can have components similar to thecomponents of the polymer coating apparatus 10 of FIGS. 1-4, and arenumbered accordingly. A single puller 89 can be used for the tandempolymer coating apparatus 86 . By using a tandem coating apparatus 86,multiple layers of polymer coating may be applied to a single elongateintracorporeal device 12 by drawing the elongate intracorporeal device12 through the first and second polymer coating apparatus 87 and 88 inserial in a direction of extrusion indicated by arrow 91. Multiplecoatings may be applied so as to be axially coextensive on the elongateintracorporeal device 12. Multiple coatings may also be applied toseparate axial portions of an elongate intracorporeal device 12 or suchthat the multiple coatings overlap each other by a desired amount.Although FIG. 7 depicts a tandem coating apparatus 86 having two polymercoating apparatus 87 and 88 in serial, any desired number of polymercoating apparatus may be used.

FIGS. 8 and 9 illustrate another embodiment of a guide tube assembly 95having features of the invention. The guide tube assembly 95 includes aguide tube 96 having an input end 97 and an output end 98 disposedpartially within a guide tube housing 101. The guide tube 96 can be madefrom a variety of polymer materials, specifically, high temperaturepolymer materials such as PI, PTFE, LCP and PEEK The guide tube housing101 has an input end 102 and an output end 103 The guide tube housing101 also has a central inner lumen 104 which is configured to accept theguide tube 96. The central inner lumen 104 of the guide tube housing 101has a retainer lip 105 at the input end 102 of the guide tube housing101 which is configured to prevent the guide tube 96 from exiting theinput end 102 of the guide tube housing 101 without blocking orinterfering with a guide chamber 106 disposed within the guide tube 96.The central inner lumen 104 of the guide tube housing 101 is capped atthe output end 103 with a retainer cap 107. The retainer cap 107 has aretainer cap top 108, a threaded portion 109 and a retainer cap insert112. The retainer cap 107, when secured to the guide tube housing 101,confines the output end 98 of the guide tube 96 within the central innerlumen 104 of the guide tube housing 101.

Disposed within the output end 98 of the guide tube 96 is a die 113which has an input end 114 and an output end 115 and which can have thesame configuration, dimensions and materials as the die 31 shown inFIGS. 5-6C. Disposed within the guide tube 96 adjacent the input end 114of the die 113 is an extrudable polymer cartridge 116 having an inputend 117 and an output end 118. An inner lumen 121 extends along alongitudinal axis 122 of the extrudable polymer cartridge 116. A pushtube 123 having a contact end 124 and an actuator end 125 is disposedwithin a guide chamber 126 of the guide tube 96 with the contact end 124adjacent the input end 117 of the extrudable polymer cartridge 116. Apush tube actuator rod 127 with an actuator rod tip 128 is disposedpartially within the guide chamber 126 with the actuator rod tip 128disposed adjacent the actuator end 125 of the push tube 123.

A heater member 131 is disposed within the guide tube housing 101 aboutthe output end 98 of the guide tube 96. The heater member 131 has aheater member housing 132, heater rods 133 and heater lead wires 134which supply power to the heater rods 133. The heater member housing 132can be made from stainless steel or any other suitable material whichcan withstand high temperatures. It may be desirable to use a materialwhich readily conducts heat for the heater member housing 132. Theheater member 131 is held in place within the guide tube housing 101 bya guide tube housing cap 135 disposed at the output end 103 of the guidetube housing 101.

The guide tube housing cap 135 can be secured to the guide tube housing101 by screws 136. The guide tube housing 101 has cooling air channels137 disposed within the housing 101 fed by air lines 138 to allow air tobe circulated about the heater member 131 and cool the heater member 131after a polymer coating process has been completed. Thereafter, a newguide tube 96, die 113, extrudable polymer cartridge 116 and push tube123 can be inserted into the guide tube assembly 95. The optionallydisposable components of the guide tube assembly 95 including the guidetube 96, die 113, extrudable polymer cartridge 116 and push tube 123 maybe replaced separately, or all at once as a modular subassembly.

The guide tube 96, die 113, extrudable polymer cartridge 116 and pushtube 123 are replaced by removing the retainer cap 107, withdrawing thespent guide tube 96, die 113, extrudable polymer cartridge 116 and pushtube 123, and then replacing a new guide tube, die, extrudable polymercartridge and push tube. The retainer cap 107 is then secured to theguide tube housing 101. The guide tube housing 101, guide tube housingcap 135 and retainer cap top 108 can all be made from a high strengthmachineable polymer insulator, such as Vespel® which is a polyimideresin based composite, or any other suitable material. An insulativematerial can be used for the guide tube housing 101, guide tube housingcap 135 and retainer cap top 108 in order to facilitate handling by theoperators of the device who must handle the various components of thepolymer coating apparatus during its operation.

The guide tube assembly 95 shown in FIGS. 8 and 9 is used in a mannersimilar to that discussed above with regard to the embodiment of theguide tube assembly 13 shown in FIGS. 1-4. The coating processparameters discussed above with regard to the embodiment of the guidetube assembly 13 shown in FIGS. 1-4, including, but not limited to,temperatures, pull speeds, rates of feed, forces on the extrudablepolymer cartridge 57, and the like, and structures and alternativestructures used to implement those parameters, can all be the same orsimilar for the embodiment of the guide tube assembly 95 shown in FIGS.8 and 9.

FIGS. 10-19 illustrate various configurations of extrudable polymercartridges having features of the invention. Specifically, FIGS. 10 and11 illustrate an extrudable polymer cartridge 141 having an input end142, an output end 143 , and a plurality of longitudinal segments 144which may be made of polymers having different compositions. Polymercomposition of the longitudinal segments 144 may vary in material type,shore hardness, color, radiopaque doping concentrations and the like. Aninner lumen 145 extends from the input end 142 to the output end, 143and is concentric with a longitudinal axis 145A of the extrudablepolymer cartridge 141. The extrudable polymer cartridge 141 can bemolded with the longitudinal segments 144 molded into place adjacenteach other. Alternatively, the longitudinal segments 144 could be moldedor extruded separately, and subsequently bonded or fused together. Also,the longitudinal segments 144 could be molded or extruded separately andput into a guide chamber 28 or 126 of the invention without being bondedor fused together.

As used herein, the term polymer, as used with regard to polymercoatings, cartridges and the like, is intended to be interpreted broadlyand include all polymers, prepolymers and the like which are suitablefor use as a coating of an elongate intracorporeal device. Somematerials suitable for the extrudable polymer cartridge 141, and allextrudable polymer cartridges discussed herein, can includepolyurethanes, including polyurethane thermoplastic elastomers;polyamides (nylons); polyethers; polyesters; polyacetals; acrylics;methacrylics; cellulosics; fluoropolastics; epoxies; keton-based resinsand polymers; polyimide based resins and polymers; bismaleimides;nitriles; polyarylates; polycarbonates; liquid crystal polymers;terephthalate resins and polymers including polybutylene terephthalateand polyethylene terephthalate; polyetherimides; polyolefins includingpolyethylenes, polypropylenes, polybutylenes, polybutadienes; polyvinylsincluding polystyrenes and polyvinyl chlorides; elastomers especiallythermoplastic elastomers; silicones; rubbers; ionomers; ceramers;dendritic polymers; and derivatives, copolymers, multipolymers, blendsand/or mixtures of any of the previous listed resins and polymers withineach group and between each group. This latter includes polyether blockamide elastomers such as COPA and PEBAX.

Any of the aforementioned polymers may be loaded with additives tocontrol the physical properties such as flexural modulus, hardness, andradiopacity. The shore hardness of an embodiment of extrudable polymercartridge 141 and embodiments of other extrudable polymer cartridgesdiscussed herein can range from about 50A to about 55D, preferably about80A to about 50D, and more preferably about 85A to about 95A.

FIGS. 12 and 13 show an extrudable polymer cartridge 146 having an inputend 147, an output end 148, a first lateral segment 149 and a secondlateral segment 150. An inner lumen 151 extends from the input end 147to the output end 148 and is concentrically located within theextrudable polymer cartridge 146. The extrudable polymer cartridge 146can be formed by molding or extruding the cartridge 146 in its finalform. In addition, the first and second lateral segments 149 and 150could be formed independently and then fused or bonded together, orplaced within a guide chamber 28 or 126 of the invention togetherwithout being fused or bonded together.

FIGS. 14 and 15 illustrate an extrudable polymer cartridge 153 having aninput end 154 and an output end 155 with an inner lumen 156 extendingfrom the input end 154 to the output end 155. The inner lumen 156 has alongitudinal axis 157 which is substantially parallel to a longitudinalaxis 158 of the extrudable polymer cartridge 153 and laterally offsetfrom the longitudinal axis 158 of the extrudable polymer cartridge 153.

FIGS. 16 and 17 show an extrudable polymer cartridge 161 having an inputend 162 and an output end 162. The extrudable polymer cartridge 161 hasa first concentric layer 164 and a second concentric layer 165 disposedabout the first concentric layer 164. An inner lumen 166 extends fromthe input end 162 to the output end 163 and is disposed concentricallywithin the extrudable polymer cartridge 161. The first concentric layer164 may have a different polymer composition from the second concentriclayer 165.

FIGS. 18 and 19 show an extrudable polymer cartridge 167 having an inputend 168 and an output end 169. A first inner lumen 170 extends from theinput end 168 to the output end 169 which may be disposed substantiallyconcentric within the extrudable polymer cartridge 167 and which issubstantially parallel to a longitudinal axis 171 of the extrudablepolymer cartridge. A second inner lumen 172 extends from the input end168 to the output end 169 and is also substantially parallel to thelongitudinal axis 171 of the extrudable polymer cartridge 167. Thesecond inner lumen 172 has a longitudinal axis 173 which is offset fromthe longitudinal axis 171 of the extrudable polymer cartridge 167. Thefirst inner lumen 170 would can encompass an elongate intracorporealdevice during an extrusion process. The second inner lumen 172 could beused to encompass a secondary elongate element such as a wire,fiberoptic, small diameter tubing or the like. The use of such anextrudable polymer cartridge 167 would facilitate application of apolymer coating to a plurality of elongate members which could be drawnthrough guide chambers 28 or 126 and extrusion orifice 68 during acoating process.

Unless otherwise described herein, conventional materials andmanufacturing methods may be used to make the guiding members of thepresent invention. Additionally, various modifications may be made tothe present invention without departing from the scope thereof. Whileparticular forms of the invention have been illustrated and described,it will be apparent that various modifications can be made withoutdeparting from the spirit and scope of the invention. Accordingly, it isnot intended that the invention be limited, except as by the appendedclaims.

What is claimed is:
 1. A method for coating an elongate intracorporealmedical device, comprising: providing a chamber having a die at one endwith an orifice and an input port at another end; providing a solidpolymer cartridge having a lumen therein inside the chamber; passing theelongate intracorporeal medical device through the input port, lumen andorifice; compressing the polymer cartridge against the die; heating thepolymer cartridge; and advancing the elongate intracorporeal medicaldevice through the orifice.
 2. The method of claim 1, wherein thepolymer cartridge includes radiopaque doping.
 3. The method of claim 1,wherein the polymer cartridge includes a plurality of longitudinalsegments including different materials.
 4. The method of claim 1,wherein the polymer cartridge includes a plurality of concentric layersincluding different materials.
 5. The method of claim 1, wherein theintracorporeal medical device is simultaneously pushed and pulledthrough the orifice.
 6. The method of claim 1, wherein the polymercartridge includes a tubular shape that is split radially at least intohalves.
 7. A method for coating a guide wire, comprising: providing achamber having a die at one end with an orifice and an input port atanother end; providing a solid polymer cartridge having a lumen thereininside the chamber; passing the guide wire through the input port,lumen, and orifice; compressing the polymer cartridge against the die;concurrently extruding the polymer cartridge through the orifice andadvancing the guide wire through the orifice; and heating the polymercartridge.
 8. The method of claim 7, wherein the polymer cartridge isheated only proximate to the orifice.
 9. The method of claim 7, whereinthe guide wire is advanced at a rate of about 0.05 to about 1.0 cm/sec.10. The method of claim 7, wherein the polymer cartridge is heated fromabout 340 to about 390 degrees Fahrenheit.
 11. The method of claim 7,wherein compressing the polymer cartridge is achieved by a force ofabout 0.5 to about 10 pounds.
 12. The method of claim 7, wherein the dieincludes a high temperature polymer.
 13. The method of claim 7, whereincompressing the polymer cartridge is achieved by a constant force. 14.The method of claim 7, wherein the die includes an inner lumen leadingto the orifice having a length of about 0.02 to about 0.5 inch.
 15. Amethod for coating a guide wire, comprising: providing a chamber havinga die at one end with an orifice and an input port at another end;providing a solid polymer cartridge; passing the guide wire through theinput port and orifice; disposing the polymer cartridge adjacent to theguide wire; compressing the polymer cartridge against the die;concurrently extruding the polymer cartridge through the orifice andadvancing the guide wire through the orifice; and heating the polymercartridge.
 16. The method of claim 15, wherein passing the guide wirethrough the input port and orifice, disposing the polymer cartridgeadjacent to the guide wire, compressing the polymer cartridge againstthe die, concurrently extruding the polymer cartridge through theorifice and advancing the guide wire through the orifice, and heatingthe polymer cartridge are repeated to produce a plurality of at leastpartially overlying coatings.
 17. The method of claim 15, wherein thepolymer cartridge includes an additive to affect at least one offlexural modulus, hardness, and radiopacity of the coating.
 18. Themethod of claim 15, wherein heating the polymer cartridge includes atleast one of softening and melting the polymer cartridge in a melt zoneproximate to the die.
 19. The method of claim 15, wherein the dieincludes an input taper and an output taper on opposite sides of theorifice.
 20. The method of claim 15, wherein heating the polymercartridge includes creating a temperature gradient longitudinally alongthe chamber.